But one American tourist got more than he bargained for when he found himself locked in, especially as he was only there to use the free WiFi.

After speaking to security guards and the police, Texan David Willis quickly turned to social media, posting an image on Instagram showing the locked doors from the inside, plus the caption: “Been here over an hour now.

“Supposedly someone is on their way.”

He later took to Twitter saying: “Hi @Waterstones I’ve been locked inside of your Trafalgar Square bookstore for 2 hours now.

“Please let me out.”

David’s call for help was retweeted more than 10,000 times, and he announced his release just before 11.30pm with another tweet saying simply: “I’m free.”

He told Good Morning Britain that he was on the third floor and did not notice the staff closing up the store below.

He said: “I get ready to leave, walk down and it’s completely dark and the door is locked.”

While described his escape attempts, he said: “I went to the door and tried to open it, the alarm went off – the alarm sounded in Trafalgar Square for probably 20 or 25 minutes.”

Sadly, David did not find much sympathy online, instead receiving helpful comments like: “You’re living the dream, David!” and: “Sounds like heaven to me.”

Others inundated him with reading suggestions, or encouraged him to start a journal of his ordeal.

Perhaps there are worst places for a tourist to be trapped, if nothing else, the WiFi signal in the London Dungeons would be atrocious.